Hemophilia...?

Hemophilia, like color-blindness, results from having the recessive gene on ALL one's X-chromosomes. For a man, that's one; for a woman, two. If the gene were dominant, only one X-chromosome would need to have it, and the daughters of hemophiliac men would have the disease rather than being carriers. And anyone with a Y chromosome is male. So you can pick the right answer.